On Thu, Jan 6, 2011 at 10:52 AM, Philip Rakity <prakity@xxxxxxxxxxx> wrote:
>
> On Jan 6, 2011, at 2:44 AM, zhangfei gao wrote:
>
>> On Wed, Jan 5, 2011 at 11:30 AM, Philip Rakity <prakity@xxxxxxxxxxx> wrote:
>>>
>>> On Jan 5, 2011, at 1:39 AM, zhangfei gao wrote:
>>>
>>>> From 7554ead744bfdc7304a7ae9fb227212bf548161a Mon Sep 17 00:00:00 2001
>>>> From: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
>>>> Date: Wed, 5 Jan 2011 17:21:00 -0500
>>>> Subject: [PATCH] mmc: sdhci stop SDCLK during asynchronous interrupt peroid
>>>>
>>>> V3 controller could stop SDCLK during asynchronous interrupt peroid
>>>> to save power, via set SDHCI_CTRL2_AINT bit 14 of
>>>> SDHCI_HOST_CONTROL2(0x3e)
>>>> Two conditions:
>>>> 1. card support asynchronous interrupt
>>>> 2. Asynchronous interrupt support is set to 1 in the capabilities register.
>>>>
>>>> How to enable: mmc->caps |= MMC_CAP_CLOCK_GATE
>>>>
>>>> Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxxx>
>>>> ---
>>>> drivers/mmc/host/sdhci.c | 14 ++++++++++++++
>>>> drivers/mmc/host/sdhci.h | 2 ++
>>>> include/linux/mmc/host.h | 2 ++
>>>> 3 files changed, 18 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>> index aafbb42..946b947 100644
>>>> --- a/drivers/mmc/host/sdhci.c
>>>> +++ b/drivers/mmc/host/sdhci.c
>>>> @@ -1261,6 +1261,15 @@ static void sdhci_set_ios(struct mmc_host *mmc,
>>>> struct mmc_ios *ios)
>>>> if(host->quirks & SDHCI_QUIRK_RESET_CMD_DATA_ON_IOS)
>>>> sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
>>>>
>>>> + if (mmc->caps & MMC_CAP_CLOCK_GATE) {
>>>> + u16 con;
>>>> +
>>>> + con = readw(host->ioaddr + SDHCI_HOST_CONTROL2);
>>>> + con |= SDHCI_CTRL2_AINT;
>>>> + writew(con, host->ioaddr + SDHCI_HOST_CONTROL2);
>>>> + }
>>>> +
>>>> +
>>>
>>>
>>> This will enable clock gating for SD/eMMC and SDIO cards. This is not a good idea for SDIO where
>>> there are known issues. This is one reason the software clock gating code does not enable
>>> clock gating on SDIO. Not all SDIO cards can work.
>>
>> It is enabled only by setting caps MMC_CAP_CLOCK_GATE, for example the
>> code to verify emmc/sd in sdhci-pxa.c
>>
>> if (pdata && pdata->flags & PXA_FLAG_CONTROL_CLK_GATE) {
>> /* v3 controller could support clock gating */
>> host->mmc->caps |= MMC_CAP_CLOCK_GATE;
>> }
>> SDIO is not enabled since no PXA_FLAG_CONTROL_CLK_GATE in flags.
>> In the experiment, we find sdio (wifi) power does not change a lot
>> with or without clock gate, it mainly rely on wifi itself, for example
>> wifi goto deep sleep mode.
>>
>
> how do you know what card will be plugged in ? this only works work hard wired cards not for cards plugged into a slot.
The SDCLK is only stopped during asynchronous interrupt peroid, it has
some clks delay after synchronous mode, according to spec, 8 clks is
needed.
So mmc, sd card should meet the requirement, but sdio may not since the variety.
Have test emmc/sd.
>
>>>
>>> It does not handle the case clock gating being supported in pre SD 3.0 controllers.
>> It is true, soft clock gating also be verified in SD 2.0 controller,
>> such as pxa955.
>>
>>>
>>> See my patch on h/w clock gating -- if there are issues with the patch would appreciate comments.
>>>
>>>> out:
>>>> mmiowb();
>>>> spin_unlock_irqrestore(&host->lock, flags);
>>>> @@ -1808,6 +1817,11 @@ int sdhci_add_host(struct sdhci_host *host)
>>>> mmc->caps |= (MMC_CAP_1_8V_DDR);
>>>> }
>>>>
>>>> + if (mmc->caps & MMC_CAP_CLOCK_GATE) {
>>>> + if (!(caps & SDHCI_CAN_ASYN_INT))
>>>> + mmc->caps &= ~MMC_CAP_CLOCK_GATE;
>>>> + }
>>>> +
>>>> if (host->quirks & SDHCI_QUIRK_FORCE_DMA)
>>>> host->flags |= SDHCI_USE_SDMA;
>>>> else if (!(caps & SDHCI_CAN_DO_SDMA))
>>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>>> index c4bd5dd..907de87 100644
>>>> --- a/drivers/mmc/host/sdhci.h
>>>> +++ b/drivers/mmc/host/sdhci.h
>>>> @@ -153,6 +153,7 @@
>>>> #define SDHCI_CTRL2_SDR104 0x0003
>>>> #define SDHCI_CTRL2_DDR50 0x0004
>>>> #define SDHCI_CTRL2_1_8V 0x0008
>>>> +#define SDHCI_CTRL2_AINT 0x4000
>>>>
>>>> #define SDHCI_CAPABILITIES 0x40
>>>> #define SDHCI_TIMEOUT_CLK_MASK 0x0000003F
>>>> @@ -172,6 +173,7 @@
>>>> #define SDHCI_CAN_VDD_300 0x02000000
>>>> #define SDHCI_CAN_VDD_180 0x04000000
>>>> #define SDHCI_CAN_64BIT 0x10000000
>>>> +#define SDHCI_CAN_ASYN_INT 0x20000000
>>>>
>>>> #define SDHCI_CAPABILITIES_1 0x44
>>>> #define SDHCI_CAN_SDR50 0x00000001
>>>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>>>> index bcb793e..2a53a94 100644
>>>> --- a/include/linux/mmc/host.h
>>>> +++ b/include/linux/mmc/host.h
>>>> @@ -173,6 +173,8 @@ struct mmc_host {
>>>> /* DDR mode at 1.2V */
>>>> #define MMC_CAP_POWER_OFF_CARD (1 << 13) /* Can power off after boot */
>>>> #define MMC_CAP_BUS_WIDTH_TEST (1 << 14) /* CMD14/CMD19 bus width ok */
>>>> +#define MMC_CAP_CLOCK_GATE (1 << 15) /* V3 controller */
>>>> + /* support clock gating */
>>>>
>>>> mmc_pm_flag_t pm_caps; /* supported pm features */
>>>>
>>>> --
>>>> 1.7.0.4
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>
>>>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
